S Ju, Y Ge, H Qiu, B Lu, Y Qiu, J Fu, G Liu, Q Wang, Y Hu, Y Shu and X. Zhang
International Immunology, 2009, 21(10), 1135-1144. DOI: 10.1093/intimm/dxp077
Dendritic cells (DCs) are responsible for the initiation of immune responses. Our study demonstrates a new pathway for generating a large quantity of stimulatory monocyte-derived DCs (Mo-DCs) from human monocytes using anti-4-1BB ligand (4-1BBL) mAb to trigger reverse signaling. The anti-4-1BBL-driven Mo-DCs (DCs-4-1BBL) not only express higher levels of CD86, CD83 and HLA-DR, when compared with the Mo-DCs matured by tumor necrosis factor , but also exhibit a unique phenotype that expresses lower levels of PD-L1. High levels of GM-CSF, M-CSF and Flt3 ligand (FL) were found in the anti-4-1BBL-differentiation culture. Neutralizing M-CSF, GM-CSF and FL inhibited Mo-DC proliferation stimulated by anti-4-1BBL mAb, suggesting that M-CSF, GM-CSF and FL are involved in cell proliferation stimulated by anti-4-1BBL. Further analysis of the DCs-4-1BBL showed increased secretion of Th1-type cytokines IL-12 and IFN- and decreased secretion of IL-10. DCs-4-1BBL induced much stronger proliferative responses in the mixed lymphocyte reaction assay when compared with DCs derived by GM-CSF. Moreover, DCs-4-1BBL preferentially induced Th1 responses. We have further demonstrated that anti-4-1BBL antibody stimulated nuclear translocation of NF-B from the cytoplasm in monocytes, suggesting that reverse signaling by 4-1BBL is likely responsible for mediating DC differentiation. Collectively, we have found that reverse signaling of 4-1BBL promotes the differentiation of potent Th1-inducing DCs from human monocytes.